Field of the Invention
The present disclosure relates to a crystalline form of (R)-3-(4-(2-(2-methyltetrazol-5-yl)pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyl oxazolidin-2-one dihydrogen phosphate, and methods of making and using the crystalline form. The crystalline form may be used as a pharmaceutically active compound in compositions that are useful in impeding the growth of bacteria or treating patients suffering from bacterial infections.
Description of the Related Art
US Patent Publication No. 20070155798, which is hereby incorporated by reference in its entirety, recently disclosed a series of potently anti-bacterial oxazolidinones including
wherein R═H, PO(OH)2, and PO(ONa)2 
Although this patent application discloses methods of making compounds such as the free acid (wherein R═PO(OH)2) and the disodium salt (wherein R═PO(ONa)2), there is no indication that any of the compounds were stably crystallized or purified. In addition, these processes include the use of reagents which are highly corrosive, such as trichloroacetic acid, or explosive, such as ethyl ether, and therefore are not suitable for commercial use. As discussed below in more detail, attempts to crystallize the disodium salt by the instant inventors resulted in a highly hygroscopic, unstable crystalline salt form which turned amorphous upon drying.
There is a need in the art for a stable, non-hygroscopic crystalline form of the free acid (wherein R═PO(OH)2) or a salt thereof that can be accurately poured and weighed for use in pharmaceutical formulations. Also, it would be advantageous if the crystalline form did not form a large number of polymorphs, as the number of polymorphs hinders the ability to reproducibly provide the identical polymorph during manufacturing. Making a particular crystalline form having these properties is an empirical process, and one skilled in the art would be unable to predict among the free acid form of the pharmaceutical compound or one of the corresponding salts, which would crystallize, if at all, under which crystallization conditions. In addition, one skilled in the art would be unable to predict which crystalline form would have the beneficial properties of stability, pourability, non-hygroscopicity and reproducibility.
In addition, improved methods of making the free acid are disclosed in U.S. patent application Ser. No. 12/577,089, which is assigned to Trius Therapeutics, Inc., and which is incorporated herein by reference. Difficulties in filtering crystalline material and processing the crystalline material into dosage forms, such as tablets, have arisen because the free acid forms fine particles which delay processing time. Therefore, there is also a need in the art for a crystalline form of the compound and related methods that overcome these processing difficulties.
In addition, it would be advantageous to have a purified compound that is suitable for pharmaceutical compositions.